Stuff you need to know…

TERMS TO KNOW!! EVOLUTION: the process by which

modern organisms have descended from ancient organisms.

(“CHANGE OVER TIME”)

 Central Idea: organisms alive today have been produced by a long process of change over time.

  FITNESS: refers to traits and behaviors of organisms that enable them to survive and reproduce

 COMMON DESCENT: species share common ancestors

  ADAPTATION: any inherited

characteristic that enhances an organism’s ability to survive and reproduce

~based on variations randomly inherited

Charles Darwin’s Explanation on Evolution

(six major ideas of Darwin)Overproduction occurs in nature

Variation occurs in all populations

Not all organisms can survive

Variations are inherited

Populations as a whole become FIT = evolved!

Organisms with favorable variations survive and reproduce

Insecticide applied

Genetic DriftChanges in the gene pool of a small

population due to chance

Examples:

-Bottleneck Effect: results from drastic decrease in population size

-Founder Effect: few individuals in a population colonize a new habitat

Bottleneck Effect

SpeciationThe origin of new species (the appearance of

new species is the source of biological diversity)

• Reproductive Isolation: barriers that prevent members of two species from producing viable, fertile hybrids

• Geographic Isolation: Gene flow between gene pools is interrupted when a population is divided into two geographically isolated subpopulations– Ex: the water level in a lake decreases– Ex: a river splits a population into two

Ecology

1) Life is ORGANIZED on many structural levels:

AtomsBiological Molecules

Subcellular organellesCells

TissuesOrgans

Organ SystemsComplex Organism

Levels beyond the individual organism:

PopulationCommunityEcosystem

BiomesBiosphere

Biodiversity

• Stability in an ecosystem is a balance between competing effects. As a basis for understanding this concept: – Students know biodiversity is the sum total of

different kinds of organisms and is affected by alterations of habitats.

• Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.

• Change in pop size = [B + I] – [D + E]

Review• Autotrophs—capture energy from

sunlight or chemicals and use that energy to produce food– AKA producers

• Photosynthesis– Plants

• Chemosynthesis– Bacteria

• Heterotrophs (Consumers)– Herbivores– Carnivores– Omnivores– Detritivores

• Feed on plant and animal remains– Mites, earthworms, snails

– Decomposers• Break down organic matter

– Bacteria and fungi

Flow of Energy

Energy flows through an ecosystem (a section of the biosphere) from the sun, to producers, to consumers

IN ONE DIRECTION!!!

Food Chains

• Food Chain—transfer of energy by eating and being eaten

Food Webs

• Food Web—describes complex relationships of organisms in an ecosystem– A food web links

together all the food chains in an ecosystem

• Shows the relative amounts of energy contained within each trophic level in a food chain or food web

• Only part of the energy that is stored in one trophic level is passed on…(10%)

• each step of an organism eating another organism is called a trophic level (trophe means food in Greek)

Tertiary Consumers

Producers

Energy Pyramid

• Approximately 10% of the energy at one trophic level can be used by animals at the next trophic level – ex: 10% of the plant's

energy is stored in the tissues of herbivores (plant eating animals) & 10% of the energy is herbivores is stored in the tissues of carnivores (animal's that eat other animals)

• More energy efficient to eat producers

• Although energy moves in a one-way direction through an ecosystem, nutrients are recycled